In the graphic arts the airbrush has long been used to produce effects which cannot be readily attained by any other means. The airbrush employs a venturi effect to aspirate paint or other liquid coloring medium into an airstream which is then directed at a work-piece such as a canvas or other usually flat surface.
The effect achieved by airbrush techniques depends upon many factors including but not limited to the pattern formed by the airstream as it emanates from the airbrush nozzle, and the standoff or separation distance between the nozzle and the workpiece. Typically, the airbrush nozzle is continuously adjustable to produce a wide range of spray patterns from a finely "focused" line to a broad fan pattern. Both the nozzle adjustment and the standoff distance affect the result, which may vary from a relatively fine line to an open pattern of tone or color, to broad ranges of color intensity variation over either wide or narrow color fields.
More specifically, the airbrush is basically a spray painting devide that can be regulated to spray fine lines to broad tonal spray patterns by atomizing a mix of air and pigment to produce an airborne mist or spray. As the atomized pigment is propelled from the airbrush, the spray develops into a circular spray pattern to produce line work which may be regulated from fine pencil like lines, to broad modulated tones or sprays patterns. A basic characteristic of all airbrushed spray patterns is a soft appearance, even when regulated to fine line settings. When the airbrush is regulated to a fine spray setting, it must be positioned close to the painting surface and when regulated to a heavy setting, it must be positioned further from the surface. The standoff distances (spacing between workpiece surface and airbrush nozzle) range from approximately 1/8" to 8" or more. As a result of this operational characteristic, the airbrush must be used in continuously spaced orientation from the painting surface at various selected standoff distances while in operation.
In order to produce forms or shapes with an airbrush, a variety of stencil techniques have commonly been used to confine the spray to specific areas, thus creating a hard edge on the contour of the form.
Airbrushing straight spray patterns may currently be produced with the aid of a raised ruler. This, however, is only possible at very fine spray settings (when the brush is placed close to painting surface). The possibility of using a ruler is eliminated once the spray setting is charged from the finest settings as this requires moving the airbrush further away from surface. Once the spray setting has been even moderately changed, the distance required between airbrush and surface for proper operation eliminates not only the possibility of using a ruler but also use of all current mechanical drafting devices, which are operative only with the drawing tool directly in contact with the drawing surface.
Airbrushing heavier spray patterns with mechanical precision (which requires substantial distancing of the airbrush from surface) without the aid of a ruler, mechanical template device or stencil, is as difficult as producing a mechanical drawing without drafting equipment.
Other factors which influence the airbrush effect include the angle of incidence of the airstream from the airbrush nozzle with respect to the workpiece surface, and perhaps most importantly the feel or touch of the airbrush artist. In this regard, the skill of the airbrush artist ultimately determines the quality of the results, just as any other tool can produce fine work or mediocrity depending upon the skill of the user.
Because of its innate versatility, the airbrush in the hands of a highly skilled artist can produce an amazing variety of artistic effects ranging from the purely abstract to pictorial renderings so detailed that they are virtually indistinguishable from photographs. From the above, both the versatility of the airbrush and one of its attendant shortcomings are apparent, namely that the range of effects the tool can produce far exceed the skill of many good artists to produce them. The teaching of airbrush technique has heretofore relied almost exclusively on the artist's innate ability to comprehend and exercise the particular mode of airbrush use which best suits him. A simple mechanical assistance device which is hand manipulated by the artist in much the same manner as though he were performing freehand airbrush work could be of considerable benefit to help the novice airbrush artist gain an appreciation of the feel of airbrush technique, although to the knowledge of this applicant, no such device has been heretofore known.
For example, U.S. Pat. Nos. 3,067,517 and 3,226,829 relate generally to drafting machines with mechanisms for producing X-Y coordinate line work; the latter of these two patents, in particular does refer to airbrush work but is a highly complex mechanism and, unlike the present invention, is not at all well adapted to permit the airbrush artist the freedom required for truly creative airbrush art.
U.S. Pat. Nos. 3,378,927 and 951,255 relate to circle drawing devices for use in conjunction with a rigid-surface drawing medium (e.g., a chalkboard as in U.S. Pat. No. 3,378,927), but are unrelated to airbrush techniques.
U.S. Pat. Nos. 2,781,582; 2,286,664 and 3,139,471 disclose various center arrangements for producing circular motion of an instrument with respect to a workpiece. These too are unrelated to airbrush techniques.
Another shortcoming of the airbrush is that the traditional modes of freehand airbrush work virtually eliminate any possibility of gaining the precision of mechanical drawings in airbrush work. Of course, this limitation has in part defined the uses to which the airbrush might be put. Thus the art has not contemplated any means of using the airbrush for precision mechanical drafting and has ignored the possibilities for new and different modes of airbrush expression which might result.
Another limitation of known airbrush technique is that the dimensional limitations on work size or proportion have been related directly to the physical limitations of the artist's body. This occurs because the artist can experience the learned feel or touch of his individual airbrush technique only in certain limited body postures. As a specific example, the physical limitations of the artist's arm extension and movement will limit the radius of arcs and curves that he can accurately render with the airbrush. This can be a severe limitation in such large scale work as stage set design and production which often requires renderings on large panels that cannot be conveniently supported in a position suitable to allow the artist complete freedom of position and movement.